Ethinyl Estradiol and Norethindrone in the Treatment of Primary Hyperparathyroidism in Postmenopausal Women

Abstract

Treatment with ethinyl estradiol or norethindrone reduces the bone-turnover rate and plasma calcium levels in normal postmenopausal women, without affecting the secretion of calcium-regulating hormones. To assess the effect of these sex steroids in patients with primary hyperparathyroidism, we treated postmenopausal women who had hyperparathyroidism with either ethinyl estradiol (n = 6) or norethindrone (n = 11). After three weeks of treatment, the bone-turnover rate declined and plasma calcium fell from a mean (±1 SE) of 2.77±0.07 mmol per liter (11.1±0.3 mg per deciliter) to 2.58+0.05 mmol per liter (10.3±0.2 mg per deciliter; P<0.01) in the group treated with ethinyl estradiol, and from 2.93±0.08 mmol per liter (11.7±0.3 mg per deciliter) to 2.84±0.08 mmol per liter (11.4±0.3 per deciliter; P<0.05) in the patients who received norethindrone. No significant changes in the plasma levels of parathyroid hormone, calcitonin, or calcitriol were observed after the estrogen-induced increases in vitamin D–binding protein had been taken into account.